Photographic light-sensitive element



May 4, 1954 B. GASPAR ET AL PI- IOTOGRAPHIC LIGHT-SENSITIVE ELEMENT Filed April 11, 1950 INVENTORS 554/7 GAjP/VP,

6057774 5 azl/vas/v, max. 0. Dela F055 A'ITORNEY- Patented May 4, 1954 UNITED STATES PHOTOGRAPHIC LIGHT SENSITIVE ELEMENT Bela Gaspar, Beverly Hills, Gustave B. Linden, North Hollywood, and Pauli). Dreyfuss, Van Nuys, Calii, assignors, by mesne assignments,

to said Gaspar Application April .11, 1950, Serial No. 155,363

4 Claims.

The present inventicnrelates to-amaterial and to a process in which easily destructible dyes incorporated in light-screeninglayers of photographic materials are completely destroyed.

In the preparation .of sensitive photographic materials it is frequently desirable to provide for one or more layers which-are colored while the material is exposed to light, but colorless in the processed material. Numerous light-screening materials, such as colloidal silver, methenil-sbispyrazolone, metal salts .of osazone derivatives of dihydroXy-tartaric acid, aminocinnamylidene ammonium quaternary salts, .etc., have been proposed for use in photographic filter or antihalation layers. removed by washing in aqueous processing baths, others are converted into colorless products in said baths, while still others can be bleached out only by treating solutions having detrimental effects on the photographic layer, the latent image, the developed silver image orin color .photographic use-the image-forming dyes. Many of the light screening materials, heretofore unknown, either diffuse or desensitize adjacent sensitive photographic emulsions. Other disadvantages encountered are that many light screening dyes are decolorized in alkaline developers'orneutral fixing baths whereby they are rendered useless in reversal materials where their presence is desired during the second exposure. Still other dyes act as color formers or they split in the developer or fixing bath to form compounds which act as color formers, i. e., compounds which later on react with color developers or diazo compounds or other dye components to form indophenol dyes, azo dyes and the like.

It is, therefore, an objectof the present invention to provide light screening layers which do not have the above namedundesirable properties. Further objects of the present invention areseen from the following:

Compounds having the general formula and salts thereof, formed by addition of acid to said compounds, where X stands for an organic radical, where Y stands for hydrogen or an organic radical, where the X-C and the Y-C bonds shown are carbon to carbon bonds, where can be part of a ring, and where Z stands for an organic residue suchas a hydrocarbon or acyl radical, are relatively stable in-alkaline and neutral processing baths butrsplit in acid baths with Some of these coloring materials are iii) 2 formation of the products X-CO-Y and Z-NI-lz which are colorless and/or can be washed out from the photographic colloid.

The instability of said compounds, such as aldiinines, ketimines and quinoneimines varies within wide limits. While layers comprising some of these imines may require as long as 30 minutes in an acid bath for complete destruction, others may bleach completely in a few seconds. A treatment for a few minutes in l-normal sulfuric or hydrochloric acid is sufficient in most cases.

Sometimes the destruction of the imine in an acid bath can be accelerated by the addition of a compound to theacid bath, which compound reacts either with the imine to form a still more easily destroyable substance, or with one of the splitting products. Particularly useful accelerators are compounds which form a reaction product containing the component :NZ, such as nitrous acid which forms the diazo compound ZNzOH, formaldehyde which forms a formaldehyde-ZNI-Iz condensation product, and the bisulfite addition product of butyraldehyde-fl-sulfonic acid.

The stablility of the imines in neutral and alkaline treating baths is a particular-advantage in reversal processes where a light screening efiect is desirable during the second exposure. Furthermore, the irnines themselves as well as the decomposition products of most of them, being unable to couple with color'developers in the presence of developable silver or with diazo compounds, are of particular value in those processes of color photography which require treatment with color developing or diazo compounds. Furthermore, in processes which require acid processing baths to produce dye images, such as in the process described in U. S. Patent 2,026,775, no additional processing step to destroy the light screening dye is required, the destruction of the light screening dye being performed simultanecusly with the local bleaching of the image-forming dyes. The imincs,.used-according to the present invention, are easily dispersed in photographic colloids, they have no detrimental effect on sensitive silver halide compositions and, if substituted in suitablemanner they do not diffuse into adjacent layers or they can be rendered nondiffusing by the addition of suitable preciptating agents. Suitableprecipitating agents for imines carrying acidic groups are, e. g., the biguanides of U. S. Patent 2,368,647, whilethe imines of basic character can be precipitated with high molecular weight acids or salts thereof such as tannic acid, sodium dodecylsulfonate or 4,4-bis-(phenylureido) -stilbene-2,2'disulionic acid. The imines are incorporated into the photographic colloid, such as gelatin, either in the formof their water soluble salts or water insoluble imines are dissolved in organic solvents such as alcohol and acetone, and these solutions are added to the photographic colloid.

It is possible, according to our invention, to use for light screening purposes, either the free imines or the salts thereof, formed by addition of acid to the imines. The color of the free imines is different, sometimes in quality, but always in quantity, from the color of the imine salts. Therefore, the pH of the photographic colloid comprising the imine must be adjusted according to what color is desired. A photographic material which is subjected to two exposures may contain the imine in different forms, e. g., it may contain during the first exposure, the free imine; after the first development it may be treated in an acid bath which is strong enough to convert the imine into its salt but which is not so strong as to destroy the imine; thereupon the material is exposed, developed and treated in a strong acid bath whereby the imine is destroyed.

Most of the imines, used in the process according to our invention have sharp absorption spectra, i. e., their presence in light screening layers permits the filtering out of a narrow band of rays. Using these imines according to the present invention, filters for a wide range of rays can be produced. Those for ultraviolet, blue and green rays are of particular importance.

A colloid containing the imines may be coated as backing on a support, or it may be coated as sublayer or toplayer or, in a multilayer material, as interlayer. The imine may be incorporated in a sensitive silver halide layer itself or in a layer adjacent to a sensitive silver halide layer. A photographic material may comprise a light screening element according to the present invention, combined with other light screening elements. E. g., five layers are coated on a support in the following order:

. A panchromatic silver halide emulsion.

A colloid comprising a red imine.

. An orthochromatic silver halide emulsion. A colloid comprising a yellow imine.

. An unsensitized silver halide emulsion.

The layers numbered 1, 3 and 5 may or may not 4 ers, is removed by washing. It is relatively stable in acids, and therefore it can be decolorized in acids only during unreasonably long processing periods.

Compounds suitable for the process disclosed herein are, e. g., the salts of 4-aminobenzaldehyde-(4-dimethylamino-anil); the sodium salt of N (4-ethy1aminobenzal)-aniline-4-sulfonic acid; the base of benzil-mono i-dimethylamino-anil); the salts of N-[3,3'-dimethyl-4- aminobiphenylyl-(Hl auramine; the salts of 3,6 di (dimethylamino) 10 thioxanthon-S- dioxyde-Q-anil; the sodium salt of the Schifl": base obtained from 2 mol of salicylaldehyde and 1 mol of benzidine2,2-disulfonic acid; all the above compounds being yellow; the nearly colorless ultraviolet light absorbing base of diphenyl- 4,4'dialdehyde-dianil; the red salts of 4-dimethylamino benzaldehyde (4 dimethylamino-anil) the salts of N-benzoylauramine and the sodium salt of anhydro-bis-(a,v-diketohydrindene)-(anil-4-sulfonic acid), which are blue. Other imines suitable for the process of this invention are disclosed in the co-pending application entitled Light Screening Photographic Layer Serial No. 155,362, filed on April 11, 1950.

Photographic materials, comprising compounds of this list are decolorized in acid treating baths such as in l-normal hydrochloric acid, in l-normal sulfuric acid or in treating baths described in U. S. Patent Re. 22,308. While the 4- dimethylaminobenzaldehyde (4-dimethylaminoanil), mentioned above, decolorizes only slowly in these treating baths, its decomposition can be accelerated by the addition of formaldehyde and still more by the addition of small amounts of nitrite to the treating bath.

The following examples illustrate in detail the process in accordance with our inventions:

Example 1 A mixture of equimolecular parts of auramine base and of ethyleneglycol bis-( i-aminophenyl) ether is melted until the evolution of ammonia ceases. The melt consisting of a compound hav ing the formula contain image forming dyes or dye components.

The imines are mostly used in such a concentration as to produce an optical density of between 1.0 and 3.0 at the Wavelength of maximum absorption. The quantity of dye required to produce such density is generally between 0.1 and 1.0 grams, per square meter.

It is obvious that our process cannot be used in those colorphotographic materials which contain image forming dyes of insufficient stability towards acids. However, our process is valuable for those materials which contain acid-stable image forming dyes or dye components such as azo dyes or azo dye components.

Light screening layers comprising such imines as auramine, condensation products of a quinone with a phenylene diamine or of a nitroso compound with a pyrazolone are already known. In these layers, according to what is known in the art, either the imine difiuses and is removed by washing, or the imine itself is the film forming substance which can be stripped oii, or the imine is not removed at all, lending the processed photographic material a diffuse color. E. g., the yellow dye auramine, used in light screening layis alkylated with three equivalents of sodium 1- bromoethane 2 sulfonate. A yellow dye can be isolated in the form of its calcium salt.

A stock solution of this dye is prepared by dissolving one gram of the calcium salt in 20 ml. of 0.1 normal sodium bicarbonate solution. The solution thus obtained is freed from small amounts of calcium carbonate by filtration. The solution is stable at room temperature, but prolonged heating should be avoided.

If, in the above alkylation, only one or two equivalents of sodium bromoethanesulfonate were used, dyes of similar properties are obtained. It is believed that part of the groups contained in these dyes are bound to a dimethylamino group and part to the external amino group.

Example 2 A silver bromide emulsion, sensitized to red light and containing N,N'-(naphthalene-1,5-disulfo) bis-1,5-aminonaphthol is coated on a transparent'support. A second silver bromide emulsion, sensitized to green light and containing 1-octadecylaminonaphthalene is coatedthereon. A solution is prepared by adding 20 ml. of the stock solution ofthe foregoing example to an aqueous gelatin solution which afterwards is neutralized by addition of '20 ml. of 0.1 normal acetic acid. This solution is coated as a filter layer on top of the green sensitiveemulsionlayer. A layer of anunsensiti-zedsilver chloride-bromide emulsion containing 1,1-"[.2;2edisulfodiphenylone-(43) l-bis- [pyrazolone carboxylic acid- (3) l and anhydrobiguanidobenzylalcohol acetate finally is coated on top of the filter layer.

Microscopic examination of a cross section of the fixed out material shows that the auramine derivative has not diffused into the colorless adjacent layers.

A material containing 7.5 ml. of the stock solution of the foregoing example per square meter has a density of about 2.0 at 480 mu, a slightly higher density at 460 mu and a density of only 0.15 at 540 mu.

Example 3 The material of Example 2 above is exposed in a camera, developed and fixed. Thereafter it is treated in a bath containing 0.1% of diazotized d-nitraniline-Z-sulfonic acid, whereby the azo coupling compound in the red sensitive layer is converted into a cyan azo dye, the azo coupling compound in the green sensitive layer is converted into a magenta azo dye and the azo coupling compound in the top layer is converted into a yellow azo dye. Thereafter the material is treated for six minutes in a bath containing 2.5% sulfuric acid, 5% sodium bromide, 1% thiocarbamide and 0.002% 2,3-diphenylquinoxaline whereby the three azo dyes are bleached in proportion to the metallic silver present and the yellow auramine derivative is diffusely destroyed. After the residual silver is removed in known manner, the material is bathed in a diluted sodium carbonate bath to stabilize the appropriate color value of the pI-I-sensitive azo dyes, and a photograph in natural colors is obtained.

The same results are obtained if the auramine derivative incorporated in the material of Example 2 is replaced with any other of the yellow filter dyes listed above, or if the diazo bath of Example 3 is followed by a l-n sulfuric acid bath whereby the auramine derivative is discharged and thereafter by the above described bleaching bath whereby the azo dyes are bleached.

Example 4 A silver bromide emulsion, sensitized to red light and containing the dye Diamine Pure Blue FF (Schultz, Farbstofftabellen, 1931, 7th edition, vol. 1, #510) is coated on an opaque support. A second silver bromide emulsion, sensitized to green light and containing the dye Benzopurpurine 4B (Schultz, l. c. #4418) is coated thereon. A layer containing sodium 4,4 di (o-hydroxybenzal) benZidine-2,2'-sulfonate is laid thereupon. A layer of an unsensitized silver bromide emulsion containing the dye Benzo Light Yellow 4 GL (Schultz, l. c. #308) finally is coated on top of this layer.

The material is exposed, developed, dye bleached, silver bleached and fixed in the usual manner. A print in natural colors is obtained.

The yellow filter dye used in this example is obtained by refluxing in aqueous sodium bicarbonate solution one mol of benzidine-2,2-disul- 6 ionic acid with a little over 2 mols of salicylaldehyde. The dye forms with-particular ease.

A layer, dyed yellow with this filter dye, is stable in alkaline photographic developers but is decolorized instantaneously by hydrolysis in the acid dyebleach bath. At least one of the hydrolytic splitting products =(the salicylaldehyde) washes out completely from the layer so that the yellow dye cannot regenerate under neutral or alkaline conditions.

Dyes which range in color from light yellow to orange and which form and decompose in analogous manner are formed from aromtaic ohydroxyaldehydes such as salicylaldehyde, orthovanilline, 1-hydroxy-Z-naphthaldehyde etc., by condensation with the salts of amino acids such as p-aminobenzoic acid, sulfanilic acid, benzidine- 2,2disulfonic acid, 4,4-diaminostilbene-2,2 disulionic acid, etc.

The accompanying drawing shows an enlarged sectional view of a multilayer photographic element provided with a light screening layer according to the invention, in which support of any suitable material is coated with light sensitive emulsion layers 2, 3 and 5, which respectively are sensitive to red, green and blue light. Between emulsion layers 3 and 5 a light screening layer t is provided which contains a colored imine according to the invention to prevent exposure of a lower emulsion layer by light which such screening layer absorbs.

I claim:

1. A photographic multilayer material including a light sensitive silver halide emulsion layer containing diffusely therein a compound selected from the group consisting of azo dyes and azo dye components and comprising at least one light screening layer containing diffusely therein a colored imine comprising the structure wherein the carbon atom shown is connected through the free valence bond shown directly to a carbon atom of an aromatic radical carrying a hydroxyl group in ortho position to the carbon atom connected to said valence bond and Z is a hydrocarbon radical carrying at least one sulfonic acid group.

2. A photographic multilayer material including a light sensitive silver halide emulsion layer containing diffusely therein a compound selected from the group consisting of azo dyes and azo dye components and comprising at least one light screening layer difiusely colored with di(o hydroxybenzal)-benzidine-2,2-disulfonic acid.

3. A photographic material comprising at least one light sensitive silver halide emulsion layer and containing at least one light screening layer containing diffusely therein a colored imine comprising the structure wherein the canbon atom shown is connected through the free valence bond shown directly to a carbon atom of an aromatic radical carrying a hydroxyl group in ortho position to the carbon atom connected to said yalence bond and Z is a hydrocarbon radical carrying at least one sulfonic acid group.

4. A photographic material comprising at least 7 one light sensitive silver halide emulsion layer and containing at least one light screening layer diffusely colored with di(o-hydroxybenzal)-benzidine-2,2-disulfonic acid.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,143,786 Mannes et al Jan. 10, 1939 10 2,203,659 Sheppard et a1 June 4, 1940 Number Number Name Date Brooker Oct. 13, 1942 Sawdey Mar. 7, 1950 Keyes et a1 Dec. 12, 1950 FOREIGN PATENTS Country Date Great Britain June 2, 1938 Great Britain Sept. 16, 1943 Great Britain May 6, 1949 

1. A PHOTOGRAPHIC MULTILAYER MATERIAL INCLUDING A LIGHT SENSITIVE SILVER HALIDE EMULSION LAYER CONTAINING DIFFUSELY THEREIN A COMPOUND SELECTED FROM THE GROUP CONSISTING OF AZO DYES AND AZO DYE COMPONENTS AND COMPRISING AT LEAST ONE LIGHT SCREENING LAYER CONTAINING DIFFUSELY THEREIN A COLORED IMINE COMPRISING THE STRUCTURE 